1. Field
The present disclosure relates generally to aircraft and, in particular, to control systems for aircraft. Still more particularly, the present disclosure relates to a method and apparatus for controlling a control surface of an aircraft.
2. Background
Flight control surfaces on an aircraft may be used to control the flight of an aircraft. Flight control surfaces may be used to adjust and control movement of an aircraft, such as flight attitude. With fixed-wing aircraft, control surfaces may be attached to an airframe on hinges and/or tracks. These control surfaces may move in a manner that deflects an airstream passing over the control surfaces. This redirection of the airstream may generate an unbalanced force to rotate the aircraft about an axis. This axis may be a vertical axis, a longitudinal axis, or a lateral axis. Movement around the vertical axis is referred to as yaw, movement around the longitudinal axis is referred to as bank or roll, and movement about the lateral axis is referred to as pitch.
In some situations, an actuator may not perform correctly to provide the desired movement. With this type of situation, redundant actuators may be present to provide movement of the control surface when the original actuator is unable to provide the desired movement.
This type of redundancy, however, may add to the weight of an aircraft. Further, by having additional redundant actuators for control surfaces, the expense to manufacture an aircraft also increases.
In these situations, the control surface may be moved to a predefined position. This operation is commonly implemented in hydraulic control actuators by means of a hydro-mechanical design commonly referred to as neutral lock or hole in the wall reversion mode.
Therefore, it would be desirable to have a system that possibly takes into account one or more of these issues as well as possibly other issues.